Film cassette with cooperating stripper and light-lock

ABSTRACT

In a film cassette, a spool is supported for rotation in an unwinding direction inside a cassette shell, a convoluted film roll whose outermost convolution is a film leader is coiled in the unwinding direction about the spool, and a film stripper is located substantially adjacent a passageway to the exterior of the shell to be received between a leading edge portion of the film leader and a next-inward convolution of the film roll responsive to rotation of the spool in the unwinding direction to divert the leading edge portion to between a pair of light-trapping pads spaced opposite each other in the passageway. According to the invention, one of the light-trapping pads is located substantially in abutment with the stripper and the other of the pads is spaced from the stripper to generally ensure the leading edge portion of the film leader will be advanced over the one pad before the leading edge portion can be advanced over the other pad when the spool is rotated in the unwinding direction.

CROSS-REFERENCE TO A RELATED APPLICATION

Reference is made to commonly assigned co-pending application Ser. No.07/679,847 entitled FILM CASSETTE WITH COOPERATING STRIPPER ANDLIGHT-LOCK, and filed Apr. 3, 1991 in the names of John J. Niedospial.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the field of photography, and inparticular to a film cassette containing roll film. More specifically,the invention relates to a film cassette that is capable ofautomatically advancing a non-protruding film leader to the exterior ofthe cassette shell responsive to unwinding rotation of a film spoolinside the shell.

2. Description of the Prior Art

In conventional 35 mm film manufacturers' cassettes, such asmanufactured by Eastman Kodak Co. and Fuji Photo Film Co. Ltd., thefilmstrip is wound on a flanged spool which is rotatably supportedwithin a cylindrical shell. A leading or forward-most section of thefilmstrip approximately 21/3 inches long, commonly referred to as a"film leader", normally protrudes from a light-trapped slit or mouth ofthe cassette shell. One end of the spool has a short axial extensionwhich projects from the shell, enabling the spool to be turned by hand.If the spool is initially rotated in an unwinding direction, the filmroll inside the shell will tend to expand radially since the inner endof the filmstrip is attached to the spool, and the fogged leader sectionprotruding from the slit will remain stationary. The film roll canexpand radially until a firm non-slipping relation is establishedbetween its outermost convolution and the inner curved wall of theshell. Once this non-slipping relation exists, there is a binding effectbetween the film roll and the shell which prevents further rotation ofthe spool in the unwinding direction. Thus, rotation of the spool in theunwinding direction cannot serve to advance the filmstrip out of theshell, and it is necessary in the typical 35 mm camera to engage theprotruding leader section to draw the filmstrip out of the shell.

A 35 mm film cassette has been proposed which, unlike conventional filmcassettes, can be operated to automatically advance a film leader out ofthe cassette shell by rotating the film spool in the unwindingdirection. The film leader originally is located entirely inside thecassette shell. Specifically, in U.S. Pat. No. 4,423,943, granted Jan.3, 1984, there is disclosed a film cassette wherein the outermostconvolution of the film roll wound on the film spool is radiallyconstrained by respective circumferential lips of two axially spacedflanges of the spool to prevent the outermost convolution fromcontacting an inner curved wall of the cassette shell. The trailing endof the filmstrip is secured to the film spool, and the forward orleading end of the filmstrip is slightly tapered purportedly to allow itto freely extend from between the circumferential lips and rest againstthe shell wall at a location inwardly of a non-lighttight filmpassageway to the outside of the cassette shell. During initialunwinding rotation of the film spool, the leading end of the filmstripis advanced along the shell wall until it reaches an inner entrance tothe film passageway. Then, it is advanced into and through the filmpassageway to the exterior of the cassette shell. The passageway has awidth that is less than the width of the filmstrip, thus resulting inthe filmstrip being transversely bowed as it is uncoiled from the filmspool, and thereby facilitating movement of the film edges under thecircumferential lips of the flanges. However, severe transverse bowingof the filmstrip in order to move its longitudinal edges under thecircumferential lips of the flanges may damage the filmstrip.

Like the type of film cassette disclosed in U.S. Pat. No. 4,423,923,commonly assigned U.S. Pat. No. 4,948,063 granted Apr. 14, 1990,discloses a film cassette that is capable of automatically advancing anon-protruding film leader to the exterior of the cassette shell inresponse to rotation of the film spool in the unwinding direction.Specifically, there is disclosed a film cassette wherein a film spool issupported for rotation in an unwinding direction inside a cassetteshell, a convoluted film roll whose outermost convolution is a filmleader is coiled in the unwinding direction about the spool, a pair offlanges are coaxially arranged along the spool to normally radiallyconfine the film roll coiled about the spool, and a film stripper islocated substantially adjacent a passageway to the exterior of the shellto be received between a leading edge portion of the film leader and anext-inward convolution of the film roll responsive to rotation of thespool in the unwinding direction to divert the leading edge portion tobetween a pair of light-trapping plush pads spaced opposite each otherin the passageway. If the film roll has been stored on the spool for anunduly long time, e.g. 10 years, it may develop what is commonlyreferred to as a "core set". The core set, in essence, manifests itselfas a lack of resistance of the film roll to being curled inward aboutthe spool. Consequently, when the spool is rotated in the unwindingdirection to move the leading edge portion of the film leader over thestripper, the leading edge portion (due to the leader's inward curl) mayfall into a space between the stripper and one of the plush pads oncethe leading edge portion is advanced beyond the stripper. Since the filmleader has a core set, it might remain in the space and cause a film jaminside the cassette shell.

Other examples of prior art possibly having the same problem may befound in commonly assigned U.S. Pat. Nos. 4,908,641, granted Mar. 13,1990, No. 4,887,776, granted Dec. 19, 1989, No. 4,883,236, granted Nov.28, 1989, and No. 4,883,235, granted Nov. 28, 1989.

The Cross-Referenced Application

The cross-referenced application discloses a film cassette wherein aspool is supported for rotation in an unwinding direction inside acassette shell, a convoluted film roll whose outermost convolution is afilm leader is coiled in the unwinding direction about the spool, and afilm stripper is located substantially adjacent a passageway to theexterior of the shell to be received between a leading edge portion ofthe film leader and a next-inward convolution of the film rollresponsive to rotation of the spool in the unwinding direction to divertthe leading edge portion to between a pair of light-trapping pads spacedopposite each other in the passageway. According to the invention, oneof the light-trapping pads is located closer to the stripper than theother of the pads and has a cut-out. The stripper is arranged in thecut-out to substantially ensure the leading edge portion of the filmleader will be advanced over the one pad before the leading edge portioncan be advanced farther than the stripper when the spool is rotated inthe unwinding direction. Thus, the leading edge portion will becontinuously supported by the stripper and/or the one pad as it entersthe passageway, thereby providing a solution to the problem posed abovein connection with the prior art examples.

SUMMARY OF THE INVENTION

In a film cassette, a spool is supported for rotation in an unwindingdirection inside a cassette shell, a convoluted film roll whoseoutermost convolution is a film leader is coiled in the unwindingdirection about the spool, and a film stripper is located substantiallyadjacent a passageway to the exterior of the shell to be receivedbetween a leading edge portion of the film leader and a next-inwardconvolution of the film roll responsive to rotation of the spool in theunwinding direction to divert the leading edge portion to between a pairof light-trapping pads spaced opposite each other in the passageway.According to the invention, one of the light-trapping pads is locatedsubstantially in abutment with the stripper and the other of the pads isspaced from the stripper to generally ensure the leading edge portion ofthe film leader will be advanced over the one pad before the leadingedge portion can be advanced over the other pad when the spool isrotated in the unwinding direction. Thus, the leading edge portion willbe successively supported without any intervening gap first by thestripper and then by the one pad as it enters the passageway, therebyproviding a solution to the problem posed above in connection with theprior art examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a film cassette according to apreferred embodiment of the invention;

FIG. 2 is an elevation view of the film cassette, illustrating thecassette shell open to reveal a film roll coiled about a film spool;

FIG. 3 is an elevation view similar to FIG. 2, through in section;

FIG. 4 is an end view partly in section of the cassette shell, the filmroll and the film spool, illustrating the manner in which the film rollis originally stored on the film spool;

FIGS. 5, 6, and 7 are end views similar to FIG. 4, illustrating themanner in which the film roll is unwound from the film spool;

FIGS. 8 and 9 are elevation views of the film roll and the film spool,illustrating the manner in which the film roll is originally stored onthe film spool;

FIGS. 10 and 11 are elevation views similar to FIGS. 8 and 9,illustrating the manner in which the film roll is unwound from the filmspool;

FIG. 12 is an exploded perspective view of the film spool without thefilm roll;

FIG. 13 is an elevation view partly in section of the film roll and thefilm spool, illustrating the manner in which a pair of film confiningflanges of the spool may be fixed via respective engagement hooks to thespool for concurrent rotation with the spool;

FIG. 14 is a blow-up of a particular portion of FIG. 13, illustratingone of the engagement hooks engaging one of the film confining flanges;and

FIG. 15 is a blow-up similar to FIG. 14, illustrating the engagementhook not engaging the film confining flange.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention is disclosed as being embodied preferably in a 35 mm filmcassette. Because the features of this type of film cassette aregenerally well known, the description which follows is directed inparticular to elements forming part of or cooperating directly with thedisclosed embodiment. It is to be understood, however, that otherelements not specifically shown or described may take various formsknown to persons of ordinary skill in the art.

Referring now to the drawings, FIGS. 1, 2 and 12 depict an improved 35mm film cassette 1 comprising a light-tight cassette shell 3 and a filmspool 5 which is rotatable about an axis X in film unwinding and windingdirections U and W within the cassette shell. The cassette shell 3consists of two shell halves 7 and 9 which are mated along respectivegrooved and stepped edge portions 11 and 13. The mated halves 7 and 9define upper and lower aligned circular openings 15 and 17 forrelatively shorter and longer opposite open-end pieces 19 and 21 of aspool core or hub 23, and they define a narrow relatively-straight filmpassageway 25 to the exterior of the cassette shell 3. The longer andshorter open-end pieces 19 and 21 of the spool core 23 each include anannular peripheral groove 27 which mates with a corresponding edgeportion 29 of the respective openings 15 and 17 in the cassette shell 3to rotatably support the film spool 5 for rotation about the axis X inthe film unwinding and winding directions U and W. A pair of blackvelvet or plush pads 31 and 32 are secured at the interior of the filmpassageway 25 to the shell halves to prevent ambient light from enteringthe film passageway. As can be seen in FIG. 4, the two plush pads 31 and32 are staggered relative to each other to extend the pad 32 furtherinward inside the cassette shell 3 than the pad 31.

A roll 33 of 35 mm filmstrip F is coiled about the spool core 23 to formsuccessive film convolutions. As shown in FIG. 3, the film roll 33includes an outermost convolution which comprises a film leader 35having a leading or forward end 37, and it includes a next-inwardconvolution 39 coiled behind the outermost convolution. The inner ortrailing end of an innermost convolution 40 of the film roll 33 issecured to the spool core 23 using known attachment means, not shown.See FIG. 13.

A pair of upper and lower identical, very thin, flexible filmconstraining flanges 41 and 43 are coaxially spaced along the spool core23 as shown in FIGS. 1, 2, 8, 12 and 13. The two flanges 41 and 43comprise respective integral disks 45 and 47 and respective integralannular lips or skirts 49 and 51 which circumferentially extend from thedisks. The two disks 45 and 47 cover opposite substantially flat sidesof the film roll 33 which are defined by corresponding oppositelongitudinal edges 53 and 55 of each successive convolution of the filmroll, and they have respective central holes 56 through which the spoolcore 23 coaxially extends to Permit rotation of the spool core relativeto the flanges 41 and 43. Respective pairs of supports 57, 57 and 57, 57are fixed to the spool core 23 to support the flanges 41 and 43 at theirdisks 45 and 47. See FIGS. 12-14. The two pairs of supports 57, 57 and57, 57 are sufficiently spaced from one another along the spool core 23to maintain respective inner faces 45' and 47' of the disks 45 and 47spaced from the longitudinal edges 53 and 55 of each successiveconvolution of the film roll 33. See FIG. 13. The annular lips 49 and 51overlap the film leader (outermost convolution) 35 of the film roll 33radially outwardly of the longitudinal edges 53 and 55 of the leader toradially confine the leader to thus prevent it from radially expandingor clock-springing into substantial contact with an interior curved wall58 of the cassette shell 3. A lip-receiving notch 59 is cut in the filmleader (outermost convolution) 35 along its longitudinal edge 55,relatively close to its leading end 37, to receive a peripheral section51' of the annular lip 51. This allows a relatively short edge-section61 of the film leader (outermost convolution) 35 connecting the leadingend 37 and the notch 59 to overlap the annular lip 51 radially outwardlyto thus maintain the leading end spaced a radial distance D from thenext-inward convolution 39 of the film roll 33. See FIGS. 4 and 9. Theleading end 37 has a forward or leading edge 63 inclined from thelongitudinal edge 53 of the film leader (outermost convolution) 35 tothe other longitudinal edge 55 of the leader to form a forward-most tipor tab 65 of the leader which, like the edge-section 61, overlaps theannular lip 51 radially outwardly. See FIGS. 1, 2, 8 and 9.

The two flanges 41 and 43 have a plurality of concentric arcuate slots66 cut in their respective disks 45 and 47 to longitudinally extend inthe film unwinding and film winding directions U and W. Engagement meansin the form of respective hook-like members 67, located on the short andlonger open-end pieces 19 and 21 of the spool core 23, are normallylocated in the concentric slots 66 for movement along the slots intoengagement with the flanges 41 and 43 responsive to rotation of thespool core relative to the flanges in the unwinding direction U and formovement along the slots out of engagement with the flanges responsiveto rotation of the spool core relative to the flanges in the windingdirection W. See FIGS. 12-15. Preferably, each of the hook-like members67 has an end face 67' that is beveled to ease the hook-like member outof one of the concentric slots 66 responsive to rotation of the spoolcore 23 relative to the flanges 41 and 43 in the winding direction W, inthe possible event the spool core is rotated relative to the flanges farenough in the winding direction to back the hook-like member out of theslot.

The two pairs of supports 57, 57 and 57, 57 are positioned to distortthe flanges 41 and 43 at their disks 45 and 47 when the hook-likemembers 67 are not in the slots 66. See FIG. 15. More specifically, inthis instance, the two pairs of supports 57, 57 and 57, 57 distort theflanges 45 and 47 in a manner such that respective flat areas 66' of thedisks located between the slots 66 are urged firmly against thehook-like members 67. This will ensure that the hook-like members 67 arereceived in the slots 66 when the spool core 23 is rotated relative tothe flanges 45 and 47 in the unwinding direction W, and thus will engagethe flanges. See FIG. 14.

A film stripper-guide 68 projects from the interior wall 58 of thecassette half 7 toward the film roll 33. The stripper-guide 68 ispositioned immediately inward of the inner entrance to the filmpassageway 25 to be received between the leading end 37 of the filmleader (outermost convolution) 35 and the next-inward convolution 39,close to the forward-most tip 65 of the leader, to pick up an edgeportion 63' of the forward or leading edge 63 of the leading end andguide it into the film passageway responsive to rotation of the spoolcore 23 in the unwinding direction U. See FIGS. 1 and 4-7. The leadingend 37 will be advanced over the stripper-guide 68 and into the filmpassageway 25, rather than between the stripper-guide and thenext-inward convolution 39, because it is spaced the radial distance Dfrom the latter convolution. Thus, as shown in FIG. 4, the leading end37 will be located within range of the stripper-guide 68 due to suchspacing D from the next-inward convolution 39.

The plush pad 32 is located closer to the stripper-guide 68 than theplush pad 31 as can be seen in FIG. 4. The closer pad 32, in essence,adjoins or abuts the stripper-guide 68. See FIGS. 1-3. This is togenerally ensure the edge portion 63' of the leading end 37 of the filmleader (outermost convolution) 35 will be advanced over the closer pad32 before the edge portion can be advanced over the other pad 31 whenthe spool core 23 is rotated in the unwinding direction U. Thus, theedge portion 63' of the leading end 37 will be successively supportedwithout any intervening gap first by the stripper-guide 68 and then bythe closer pad 32 as it enters the film passageway 25.

When the leading end 37 of the film leader (outermost convolution) 35 isadvanced over the stripper-guide 68 responsive to rotation of the spoolcore 23 in the unwinding direction U, the longitudinal edges 53 and 55of the leader start to gently flex respective arcuate portions of thetwo flanges 41 and 43 away from one another, i.e. farther apart, firstto allow the notch 59 to separate from the lip section 51', and then toallow successive longitudinal sections of the leader to uncoil frombetween the flanges and exit to the outside of the cassette shell 3. SeeFIGS. 10 and 11. The flexing of the flanges 41 and 43 occurs because thefilm width W_(F) between the longitudinal film edges 53 and 55 isslightly greater than the axial spacing A_(S) between the annular lips49 and 51. Moreover, successive convolutions of the film roll 33 have aresistance to transverse bowing that is greater than the resistance ofthe flanges 41 and 43 to be flexed. Two pairs of flat curved bearingmembers 69 project from the interior walls 58 of the respective shellhalves 7 and 9 to lie flatly against successive arcuate portions of thetwo disks 45 and 47 as the flanges 41 and 43 are flexed away from oneanother, to only allow those flange portions separated from the bearingmembers to be flexed farther apart. See FIGS. 1, 2 and 4. The bearingmembers 69 are positioned relatively remote from the film passageway 25.Thus, the leader 35 is only allowed to uncoil from between the flanges41 and 43 relatively close to the passageway 25. See FIG. 7.

A film flattening rib 71 projects from the interior wall 58 of thecassette half 9 in the vicinity of the inner entrance to the filmpassageway 25 and the stripper-guide 68 to support successivelongitudinal sections of the film leader 35 substantially flat widthwiseas those sections are freed from the flanges 41 and 43, to facilitatemovement of such sections into the passageway. See FIGS. 1 and 7. Twosubstantially parallel curved film supporting ribs 75 and 76 projectfrom the interior wall 58 of the cassette half 7 to longitudinallyextend from the film flattening rib 71 to part-way between the pair ofbearing members 69 which project from the same wall. See FIGS. 1, 3, and4. The film supporting ribs 75 and 76 longitudinally extend the entirelocation at which the film leader (outermost convolution) 35 can escapethe confinement of the flanges 41 and 43, when the leader axially flexesthe flanges away from one another. The film supporting ribs 75 and 76 asshown in FIG. 3 are positioned to be slightly spaced from the filmleader 35, when the leader is confined within the annular lips 49 and51. Another film supporting rib 77 projects from the interior wall 58 ofthe cassette half 7, opposite the stripper-guide 68. The other rib 77 issubstantially parallel to and shorter than the first two ribs 75 and 76.All three of the ribs 75-77 longitudinally extend perpendicular to andadjoin the flattening rib 71. See FIG. 1.

Operation

When the spool core 23 is initially rotated in the film unwindingdirection U, the two flanges 41 and 43 momentarily tend to remainstationary and the film roll 33, since its inner end is attached to thespool core, will expand radially or clock-spring to force the filmleader (outermost convolution) 35 firmly against the annular lips 49 and51 of the flanges. Generally however, before the film roll 33 can beexpanded radially to the extent a non-slipping relation would be createdbetween the film leader (outermost convolution) 35 and the annular lips49 and 51, the hook-like members 67 will have moved along the respectiveslots 66 (or from the flat areas 66' into the slots 66, and then) intoengagement with the two flanges 41 and 43 to fix the flanges to thespool core. Then, further rotation of the spool core 23 will similarlyrotate the flanges 41 and 43. As a result, the leading end 37 of thefilm leader (outermost convolution) 35 will be advanced over the shorterrib 77 and the stripper-guide 68, causing successive arcuate portions ofthe flanges 41 and 43 to be flexed away from one another as shown inFIG. 11. This first allows the notch 59 to separate from the lip section51', and then it allows successive longitudinal sections of the filmleader 35 to exit from between the flanges to the outside of thecassette shell 3. Since the stripper-guide 68 initially picks up theleading end 37 of the film leader 35 close to its forward-most tip 65,the edge portion 63' of the forward edge 63 of the leading end may moveagainst the film flattening rib 71.

If the spool core 23 is rotated in the film winding direction W aftersome length of the filmstrip F has been advanced from the cassette shell3, the spool core is free to rotate relative to the two flanges 41 and43 because the hook-like members 67 can move along the respective slots66 out of engagement with the flanges. This permits the flanges 41 and43 to be independently rotated in the winding direction W, though at aslower speed than the spool core 23 is rotated in that direction. Eachof the hook-like members 67 may back out of one of the slots 66 and intothe next slot during continued rotation of the spool core 23 in thewinding direction W. At the same time, the filmstrip F will be rewoundonto the spool core 23 between the flanges 41 and 43.

The invention has been described with reference to a preferredembodiment. However, it will be appreciated that variations andmodifications can be effected within the ordinary skill in the artwithout departing from the scope of the invention.

We claim:
 1. An improved film cassette wherein (a) a spool is supportedfor rotation in an unwinding direction inside a cassette shell, (b) aconvoluted film roll whose outermost convolution is a film leader iscoiled in the unwinding direction about said spool, and (c) a filmstripper is located substantially adjacent a passageway to the exteriorof said shell to be received between a leading edge portion of said filmleader and a next-inward convolution of said film roll, when said spoolis rotated in the unwinding direction, to divert said leading edgeportion to between a pair of light-trapping pads spaced opposite eachother in said passageway, and wherein the improvement comprises:one ofsaid light-trapping pads is located in abutment with said stripper andthe other of the pads is spaced from the stripper to generally ensurethe leading edge portion of said film leader will be advanced over saidone of the pads before said leading edge portion can be advanced oversaid other of the pads when said spool is rotated in the unwindingdirection.
 2. The improvement as recited in claim 1, wherein said one ofthe pads that is located in abutment with said stripper extends closerto said film roll than said other of the pads.
 3. The improvement asrecited in claim 1, wherein said one of the pads that is located inabutment with said stripper extends further inward inside said shellthan said other of the pads.
 4. An improved film cassette wherein (a) aspool is supported for rotation in an unwinding direction inside acassette shell, (b) a convoluted film roll whose outermost convolutionis a film leader is coiled in the unwinding direction about said spool,and (c) a film stripper is located substantially adjacent a passagewayto the exterior of said shell to be received between a leading edgeportion of said film leader and a next-inward convolution of said filmroll, when said spool is rotated in the unwinding direction, to driversaid leading edge portion to between a pair of light-trapping padsspaced opposite each other in said passageway, and wherein theimprovement comprises:said light-trapping pads are staggered relative toeach other, with one of the pads extending further inward inside saidshell than the other of the pads and contacting said stripper togenerally ensure the leading edge portion of said film leader will beadvanced over said one of the pads before said leading edge portion canbe advanced over said other of the pads when said spool is rotated inthe unwinding direction.